New series of MRAS for speed estimation of vector controlled induction motor drive

A unique formation of model reference adaptive reference (MRAS) using, active power (P), reactive power (Q) and fictitious quantities (X and Y) as the functional candidates is presented. The formulation of MRAS in the proposed form has the advantage that, no machine parameters are involved, except the rotor resistance. The reference and adjustable model of modified MRAS are computed in rotating reference frame, using reference value of voltages and currents in the reference model, whereas, reference voltages and actual currents in the adjustable model. Stability analysis of the modified P, Q, X and Y based MRAS is performed in all the four quadrants of speed-torque domain. It is found that P and Y MRAS have unstable points, whereas, Q and X MRAS are stable in all the four quadrant of operation. The algorithm can be implemented without the need of any extra hardware, thus making it suitable for retrofit applications. The proposed MRAS based speed sensorless vector controlled IM drive have been simulated in MATLAB/SIMULINK and is experimentally validated with the laboratory developed prototype. The prototype is built around a dSPACE 1104 controller board.